Good post
Anyway, to clarify:
An INFJ in Myers-Briggs uses Ni, Fe, Ti and Se (I'm not sure in what manner though--someone else fill in for me here).
An INFj (or EII, or FiNe, or Dostoyevsky) in Socionics primarily lives in a world of Fi: they know what people feel about and expect of themselves and others. The focus on this Fi leads to two weaknesses; one of which is conscious, the other is unconscious due to the intense focus on the "base" function (Fi for an EII). Due to the Fi focus, they inherently have difficulty with the Ti realm of impersonal ideals. Also, due to living in a world of "moral imperatives", they tend to neglect (not consciously, mind you) practical reasons for doing things, instead living in a world of "This is what is expected of me, this is what I will do". I haven't figured out how to address how they use Fe, but it's inherently linked to a conscious weakness in Ti.
Those functions are known as the "accepting" functions. They're all built around complementary pairs, one of which is conscious, the other of which is a resulting behavioural trait. They're called "accepting" because they're how you passively accept information.
The functions are known as the "producing" functions. The thing that sits next to Fi, called Ne, is called the "creative" function. The entire producing line is how you interact with other people. For introverts (XXIs), that's creating something worth being included for. In EIIs, that's achieving their own high internal standards. Due to focusing on the intangible, they're often not able to defend themselves in the "now", 'because I'm still getting there'. Due to this focus on Ne, they often have an idea of how things should be, and how to get there; but often fall prey to materializing such visions "later" (not sure how the dynamic works here).
So, in other words, you only use your two ego functions. The rest are byproducts, essentially.
This wikisocion page explains the functions and how they're related.
Practical example time!
It can be useful to look at intertype relations as trades involving psychological services.
I'm an IEE, so my dual is the SLI. SLIs are incredibly adaptable creatues, so much so that they often have no idea how to break out of things, and get "stuck" just adapting constantly. I value this: they're stable, without being boring. At the same time, I'm naturally able to see a horrid tangled mess of potentials and alternates, which they value. I turn the pond into a brook, so to speak. Out of that I get a burbling brook to chillax and enjoy
One of the jobs of the Extravert in socionics is creating a context or environment to facilitate interactions. I do that with Fi, or reaching out to people and inviting them to open up and share their opinions and experiences. Additionally I verbally reinforce the status of a relationship, something which SLIs can't assess too easily (which leads to them being very loyal and patient, which is a plus). I also tend to accumulate vast amounts of information, albeit in a very low-resolution and fairly unstructured form. I've found that SLIs are naturally good at filtering through this and making sense of it all
I'd say additionally they strike me as knowledgable, and I value knowing things
That's about all the ramble I can squeeze out of myself. I have no idea if any of it is useful or not.
EDIT
Don't hold me to my EII description, btw. I was just trying to use it as an example for how everything in a Socionics type is linked up.
